Polymer composition, absorbent material composition, their production and their use

ABSTRACT

A polymer composition, a process for the production of a polymer composition, in particular of an absorbent, are disclosed which substantially consist of a special component A based on renewable polysaccharide raw materials, a special component B consisting of a water-soluble polymer, a matrix material, an ionic and/or covalent cross-linking agent, or an anti-blocking agent, which is obtainable in that the water-swellable polymer is brought together with the polysaccharide polymer, that these are dried and ground then, the other components are added, and mixing up to homogeneity is effected followed by a heat treatment, and that during the addition of the cross-linking agent, after said heat treatment, the same is optionally fixed by the matrix by means of a final heat treatment. 
     Additionally the use of this polymer composition and (animal) hygiene items and chemico-technical products are disclosed which comprise a previously manufactured polymer composition.

The present invention relates to polymer material compositions and tothe production of a polymer composition and in particular absorbingmaterials mainly based on renewable raw materials. For this reason theyare biodegradable in principle. Owing to the mainly native origin theabsorbents do not comprise residual monomers, or considerably loweramounts thereof, as compared with absorbers based on polyacrylate. Theabsorbers according to the present invention have a comparatively highabsorption capacity and absorption rate, also under load, for water andaqueous solutions, no tendency to gel blocking (gel blocking: on contactwith water the outer layers of the absorber stick together and preventfurther advancement of the liquid into the absorber), and they aremechanically stable (with respect to the separation into the individualcomponents). In swollen condition they separate into individualparticles; they are non-aqueous and have a very high gel stability. Thepresent invention further relates to a process for their production andto their use as fiber, film, powder, or granular material for theabsorption of water, aqueous solutions or aqueous dispersions and bodyfluids in hygiene articles, such as tampons or diapers, in animalhygiene articles, in technochemical products, for example, packagingmaterials, in particular for meat and fish, in culture pots, as well asin soil conditioning and as cable sheathings.

Most of the absorbing materials used today, also referred to assuperabsorbers, which are capable of absorbing large amounts of liquid(water, urine) within a short period of time, primarily are slightlycross-linked polyacrylates; therefore they are not based on renewableraw materials and their biodegradability is comparatively insufficientor they are not biodegradable at all.

Endeavoring to build up superabsorbers of renewable raw materials,acrylic acid was grafted on polysaccharides, for example on corn starch,as is described in DE-PS 2612846. However, only small amounts ofpolysaccharides (up to a maximum of 25%) may be used, since otherwisethe absorption properties will deteriorate dramatically.

By incorporating polysaccharides into the polymerization gel ofpolyacrylates, as is described in DE-OS 40 29 591, 40 29 592, and 40 29593, the polyacrylates can also only be replaced to the extent of amaximum of 25%, without resulting in a clear deterioration of theabsorption capacity and other properties of the resultingsuperabsorbers, even if various auxiliary agents are added additionally,such as fibers and, for example, aluminum cross-linkers. Thepolysaccharides are considered to be fundamental elements for theabsorbers to obtain biodegradable units.

DE-PS 3132976 describes the mixing of polyacrylic acid withpolysaccharides in powdery form and in solution, wherein the shell ofthe absorber particles of the mixtures are cross-linked with aluminumcross-linking agents, such as Al(OH)₂ OCCH₃ *1/3H₃ BO₃. Thus, thisprocess cannot provide superabsorbers consisting by more than 60% ofrenewable raw materials.

According to the processes described in the art, the polysaccharides donot contribute much as an absorption component.

Various publications, such as DE-OS 2634539, describe the production ofcarboxymethylcellulose-absorbers, i.e., of materials which arebiodegradable in principle, by cross-linking the carboxymethylcellulosewith various cross-linking agents in aqueous system. However, theseabsorbers show severe gel blocking. U.S. Pat. No. 4,959,341 describesthe production of an absorber based on carboxymethylcellulose, whichconsists of a mixture of carboxymethylcellulose, cellulose fibers, ahydrophobic component, and Al(OH)₂ OOCCH₃ *1/3H₃ BO₃ as cross-linkingagent, the aluminum cross-linking agent causing a cross-linkage of thecarboxymethylcellulose during the liquid absorption. These absorbershave good absorption properties, however, show blocking phenomena.Additionally, these absorbers can easily be separated by mechanicalstress, such as sieving or conveying, so that they are no longer presentas a homogeneous product, this restricts their applicability to a greatextent.

EP-PS 0 201 895 also describes the production of an absorber based oncarboxymethylcellulose. However, in the production of these absorbers anaqueous solution is used in which the carboxymethylcellulose is presentin a low concentration. Additionally, larger amounts of organicsolvents, such as acetone, methanol, and the like are required in theproduction. The production of these carboxymethylcellulose-absorbers isvery time-consuming. The absorbers themselves show blocking phenomenaand have a low gel strength.

Initially, only the very high swelling capacity on contact with aliquid, also referred to as free swelling capacity, had been the mainfactor in the development of superabsorbers; later it turned out,however, that not only the amount of absorbed liquid is of importancebut also the gel strength. However, absorbency, also referred to asswellability or free swelling capacity, on the one hand, and gelstrength of the cross-linked polymer on the other hand, representedcontrary properties, as is known by U.S. Pat. No. 3,247,171 (DOW/WALKER)and US-PS Re 32,649. This means that polymers having a particularly highabsorbency exhibit a poor strength of the swollen gel so that the gel isdeformable under an exerted pressure (e.g., load of a body) and furtherliquid distribution and liquid absorption is prevented. According toUS-PS Re 32,649 a balanced relation between absorption capacity (gelvolume) and gel strength should be aimed at so as to ensure liquidabsorption, liquid transport, dryness of the diaper and the skin whenthese superabsorbers are used in a diaper construction. In thisconnection, not only is the polymer's capability of retaining a liquidunder subsequent pressure, after swelling freely first, of importance,but also the fact that liquids are absorbed even against asimultaneously acting pressure, i.e., during the liquid absorption. Thisis the case in practice when a baby or person sits or lies on a sanitaryarticle or when shear forces are acting, e.g., by movements of legs. InEP-A-0 339 461, pages 5 to 7, this specific absorption property isreferred to as absorption under load ("AUL").

It was the object of the present invention to provide and produce apolymer composition, in particular an absorber, which does not have thedrawbacks described above and has the following properties:

a) The absorber shall mainly consist of components of a native originand thus be biodegradable in principle.

b) The absorbers shall have a high mechanical strength, they must notseparate into their individual components during sieving or, forexample, in a helical screw feeder.

c) The absorbers shall have a comparatively high absorption rate andabsorption capacity for water and aqueous solutions.

d) The content of residual monomers shall be considerably lower than inconventional absorbers based on polyacrylates.

e) The absorbers shall have a very high gel stability in swollencondition; in this connection the absorber particles shall be present inthe form of separated, individual particles.

f) They must not show a tendency to gel blocking.

g) The absorbers shall have a high absorption rate and absorptioncapacity under load for water and aqueous solutions.

Another object is the provision of an active substancecontaining-composition, its production and use.

According to the present invention the solution of the first object isachieved by a polymer composition and a process for the production of apolymer composition, in particular an absorbing material, substantiallyconsisting of four components:

a component A based on reproductive special raw materials,

a component B consisting of a special water-swellable polymer,

a matrix material, and

an ionic or covalent cross-linking agent,

optionally, of an anti-blocking agent.

The present invention relates to a polymer composition, in particular anabsorbent material composition, substantially consisting of70-99.99%-wt. of a component A based on water-soluble and/orwater-swellable polymers based on polysaccharides and their derivativeswhich have optionally been modified by cross-linkage, and 0.01-30%-wt.of a component B based on water-swellable, synthetic polymers and/orcopolymers based on (meth-) acrylic acid, (meth-) acrylonitrile, (meth-)acrylamide, vinyl acetate, vinyl pyrrolidone, vinyl pyridine, maleicacid (-anhydride), itaconic acid (-anhydride), fumaric acid, vinylsulfonic acid, and/or 2-acrylamido-2-methylpropane sulfonic acid, aswell as the amides, N-alkyl derivatives, the N,N'-dialkyl derivatives,hydroxyl group-containing esters and amino group-containing esters ofthese polymerizable acids, with 0-98% of the acid groups of these acidsbeing neutralized, and these polymers and/or copolymers beingcross-linked by an at least bifunctional compound, used as polymercomponents, and 0.1-30%-wt., relative to these polymer components, of amatrix material having a melting or softening point of below 180° C. forthe prevention of separation and gel blocking, 0.001-10%-wt., relativeto these polymeric components, of an ionic or covalent cross-linkingagent, and optionally 0-50%-wt., relative to these polymer components,of at least one anti-blocking agent based on natural and/or syntheticfibers and/or large-surface materials, obtainable by bringing togethercomponent B with component A in aqueous medium, subsequent drying andgrinding, adding the further components, mixing up to homogeneity, andcarrying out a heat treatment, and during the addition of thecross-linking agent after said heat treatment optionally carrying out afinal heat treatment to fix the cross-linking agent with the matrix.

The present invention therefore further relates to a process for theproduction of a polymer composition, in particular an absorbentmaterial, substantially consisting of 70-99.99%-wt. of a component Abased on water-soluble and/or water-swellable polymers based onpolysaccharides and their derivatives which have optionally beenmodified by cross-linkage, and 0.01-30%-wt. of a component B based onwater-swellable, synthetic polymers and/or copolymers based on (meth-)acrylic acid, (meth-) acrylonitrile, (meth-) acrylamide, vinyl acetate,vinyl pyrrolidone, vinyl pyridine, maleic acid (-anhydride), itaconicacid (-anhydride), fumaric acid, vinyl sulfonic acid, and/or2-acrylamido-2-methylpropane sulfonic acid, as well as the amides,N-alkyl derivatives, the N,N'-dialkyl derivatives, hydroxylgroup-containing esters and amino group-containing esters of thesepolymerizable acids, with 0-98% of the acid groups of these acids beingneutralized, and these polymers and/or copolymers being cross-linked byan at least bifunctional compound, used as polymer components, and0.1-30%-wt., relative to these polymer components, of a matrix materialhaving a melting or softening point of below 180° C. for the preventionof separation and gel blocking, 0.001-10%-wt., relative to thesepolymeric components, of an ionic or covalent cross-linking agent, andoptionally 0-50%-wt., relative to these polymer components, of at leastone anti-blocking agent based on natural and/or synthetic fibers and/orlarge-surface materials, characterized in that it is obtained bybringing component B together with component A in aqueous medium,subsequent drying and grinding, adding the other components, mixing upto homogeneity, and carrying out a heat treatment, and during theaddition of said cross-linking agent after said heat treatmentoptionally fixing the cross-linking agent with the matrix by means ofcarrying out a final heat treatment.

Most surprisingly, it was found that in the production a slight additionof component B to component A results in a distinct improvement in theabsorption properties. Since only slight additions of component B arerequired, the residual monomer content, e.g., of acrylic acid, of suchan absorber is clearly lower than that of absorbers based onpolyacrylates. The incorporation of component B into component A isachieved, for instance, by joint swelling in water or an aqueoussolution and subsequent drying. Most surprisingly, this method resultsin a clear increase of the AUL-value; additionally, the portion ofcomponent B can surprisingly be reduced to a considerable extent,without impairing the absorption properties of the product. Furthermore,it was surprisingly found that through the addition of a solid matter,which serves as a matrix for the absorber system, in combination withthe polymer absorbent, a mixture of the components A and B, and an ioniccross-linking agent, an absorbent can be produced which has a highabsorption rate and absorption capacity for water and aqueous solutionsas well as an improved mechanical strength with respect to separation ofthe individual dry particles. Additionally, the gels of this absorbersystem are present separately in individual particles.

Most surprisingly, these absorbers, in addition to the above-mentionedproperties, additionally have a gel strength that is considerably higherthan that of absorbers built up on a polyacrylic acid basis.

Water-soluble and water-swellable polymers based on polysaccharides andtheir derivatives are suitable as component A, such as guar,carboxymethyl guar, xanthan, alginates, gum arabic,hydroxyethylcellulose or hydroxypropylcellulose, carboxymethylcelluloseand other cellulose derivatives, starch and starch derivatives, such ascarboxymethyl starch and mixtures of the individual polysaccharides. Thepreferred polymers are guar as well as the anionic derivatives ofstarch, guar and cellulose, with carboxymethylcellulose representing aparticularly preferred material.

The listed polymers of component A may be modified by a cross-linkage inorder to reduce their solubility in water and to achieve better swellingproperties. The cross-linking may take place both in the whole polymeror only on the surface of the individual polymer particles.

The reaction of the polymers may be effected with ionic cross-linkers,for example, calcium, aluminum, zircon, iron(III), and titaniumcompounds. The reaction may also be effected with polyfunctionalcarboxylic acids, such as citric acid, mucic acid, tartaric acid, malicacid, malonic acid, succinic acid, glutaric acid, adipic acid, withalcohols, such as polyethylene glycols, glycerol, pentaerythritol,propanediols, saccharose, with carbonic acid esters, such as ethyleneand propylene carbonate, with amines, such as polyoxypropylene amines,with epoxy compounds, such as ethylene glycol diglycidyl ether, glycoldiglycidyl ether or glycol triglycidyl ether and epichlorohydrin, withacid anhydrides, such as succinic anhydride and maleic anhydride, withaldehydes and polyfunctional (activated) olefins, such asbis-(acrylamido)-acetic acid and methylene bisacrylamide. As a matter offact, also suitable are derivatives of the mentioned compound classes aswell as heterofunctional compounds with different functional groups ofthe above-mentioned compound classes.

Suitable as component B are water-swellable synthetic polymers orcopolymers primarily based on (meth-) acrylic acid and also based on(meth-) acrylonitrile, (meth-) acrylamide, vinyl acetate, vinylpyrrolidone, vinyl pyridine, maleic acid, maleic anhydride, itaconicacid, itaconic acid anhydride, fumaric acid, vinyl sulfonic acid,2-acrylamido-2-methylpropane sulfonic acid, as well as the amides, theirN and N,N'-dialkyl derivatives, hydroxyl group-containing esters andamino group-containing esters of the polymerizable acids. Cross-linked,partially neutralized polyacrylates are preferred.

Up to 98%, preferably 50-80%, of the acid groups may be neutralized.

The polymers may be cross-linked by an at least bifunctionalcross-linking agent.

The production of above polymers is effected according to knownprocesses (DE-PS 27 06 135, DE-OS 40 15 085). Polyacrylates, e.g., theFAVOR®-types manufactured by Chemische Fabrik Stockhausen GmbH,represent a particularly preferred material as component B.

The components A and B may either be combined chemically, i.e., viaester bonds or by one of the listed cross-linking agents, or physically,i.e., in the sense of an interpenetrating network (IPN).

Organic solid substances melting or softening below 180° C. andpreferably having a soft consistency at room temperature are suitable asmatrix, for example, triglycerol monostearate. Highly viscous liquids,such as castor oil are also suitable. For preference, polycaprolactonesare suitable as the matrix, such as TONE 0230 and 0240 from UnionCarbide, which may also be modified, e.g., by a reaction with maleicanhydride.

The matrix imparts a higher mechanical strength to the absorber system,presumably by chemical and/or physical interactions; this considerablyreduces the separation of the individual components during transports,e.g., by means of a conveyor screw or by screening. Thereby an absorbentcan be manufactured which has high absorption values and, moreover, ispresent as a more homogeneous and thus more effective system, afterfinishing or incorporation into its intended place. Additionally,embedding the absorption agent in the matrix most surprisingly resultsin a clear reduction or even complete elimination of gel blocking, thusensuring a high absorption rate throughout the absorber. Furthermore,the matrix firmly fixes the cross-linking agent at the surface of theindividual absorber particles. The granulation of superabsorber finedusts by means of agglomeration auxiliary agents is described in theexamples of DE-PS 37 41 157 and DE-PS 39 17 646. The products thusproduced have a high absorption rate for water and aqueous solutions.However, they completely consist of polyacrylates and for this reasonare poorly--if at all--biodegradable. The agglomeration agents merelyhave a function in the granulation of a product, but not as a matrixmaterial.

The anti-blocking agents reduce also gel blocking; thus they cause anaccelerated and improved liquid absorption and ensure that the gels areseparated, i.e., are present as individual particles. As is generallyknown, suitable anti-blocking agents include fibrous materials and otherlarge-surface materials (cf. DE-PS 31 41 98 and DE-PS 33 13 344).

The fibers may be natural or synthetic ones, e.g., wool, cotton, silkand cellulose fibers, or polyamide, polyester, polyacrylonitrile,polyurethane fibers, fibers of olefins and their substitution products,as well as polyvinyl alcohol fibers and their derivatives. Examples ofinorganic materials include, bentonites, zeolites, aerosils, andactivated carbons.

Suitable cross-linking agents are compounds converting theabove-mentioned polymers into a state in which the water-solubility isreduced, the suction power improved, and the block phenomena diminished.

Metallic compounds which can interact with the functional groups of thepolymers are suitable ionic cross-linking agents. Particularly preferredare magnesium, calcium, aluminum, zircon, iron, titanium, and zinccompounds which have an excellent solubility in water, such as the saltsof carboxylic acids and inorganic acids. Preferred carboxylic acids areacetic acid, lactic acid, salicylic acid, propionic acid, benzoic acid,fatty acids, malonic acid, succinic acid, glutaric acid, adipic acid,citric acid, tartaric acid, malic acid, and mucic acid. Preferredinorganic anions include chlorides, bromides, hydrogensulfates,sulfates, phosphates, borates, nitrates, hydrogencarbonates, andcarbonates. Additionally suitable are organic compounds comprisingmulti-valent metals, such as actylacetonates and alcoholates, e.g., ironand zirconium acetylacetonates such as Fe(acac)₃, and Zr(acac)₄, andtitanium and zirconium alcoholates of butanol and propanol such asTi(OBu)₄ and Zr(o-prop)₄.

The water-soluble cross-linking agent causes a cross-linkage of thecomponents A and B, both with each other and between each other, inparticular at the surface, thus improving the absorption properties, asis described in DE-PS 31 32 976, DE-PS 26 09 144, and U.S. Pat. No.4,959,341.

Suitable covalent cross-linking agents are polyfunctional carboxylicacids, alcohols, amines, epoxy compounds, carboxylic acid anhydrides,and aldehydes as well as their derivatives. Examples thereof includecitric acid, mucic acid, tartaric acid, malic acid, malonic acid,succinic acid, glutaric acid, adipic acid, polyethylene glycols,glycerol, propanediols, polyoxypropylene amines, epichlorohydrin,ethylene glycol diglycidyl ether, glycol diglycidyl ether, succinicanhydride, maleic anhydride, ethylene carbonate and propylene carbonate.Also suitable are natural derivatives of the listed compounds as well asheterofunctional compounds with different functional groups of theabove-mentioned compound classes.

The proportion of component A in the ratio of component A to component Bamounts to 70-99.99%-wt., preferably 75-95%-wt. The portion of componentB amounts to 0.01-30%-wt., preferably 5-25%-wt.

The addition of component B--even in small amounts--causes aconsiderable improvement in the absorption properties, in particularwith respect to the suction power. As compared to a purecarboxymethylcellulose material (C.M.C.-material) a surprisingly clearimprovement in the absorption properties can thereby be achieved.

The required portion of component B is considerably reduced by aprocessing of components A and B, for instance, in swollen condition andsubsequent drying.

The amount of anti-blocking agent preferably amounts to between 0.5 and50%-wt., particularly preferred 5 to 15%-wt., relative to components Aand B.

The amount of cross-linking agent in the absorber amounts to0.001-10%-wt., preferably 3-7%-wt., relative to components A and B.

The addition of matrix material, relative to components A and B, shallamount to between 0.1-30%-wt., preferably between 2.5 and 7.5%-wt. Thematrix material prevents the absorbent from disintegrating, as isobserved in pure physical mixtures, e.g., in U.S. Pat. No. 4,952,550,and it additionally prevents gel blocking.

The preferred production of the absorbent is described in the following.

Step 1) Component A and component B are physically mixed in dry form atroom temperature. Then they are allowed to swell together in water or inan aqueous solution under stirring. After 15 to 360 minutes, theobtained material is dried at 40° C. to 180° C. in a drying oven. Theobtained product is dried then.

Step 2) The obtained material is mixed with the anti-blocking agent andthe matrix component until a homogeneous mixture results. Mixing of thecomponents is effected in suitable mixers, such as screw mixers,fluidized bed mixers, disk mixers, or ribbon mixers. Then, a heattreatment step is carried out.

The heat treatment is effected at 25° C. to 180° C., preferably at 100°C. to 120° C. The heating time amounts to 5 to 60 minutes, preferably 20to 40 minutes. Conventional dryers or heating furnaces or ovens (e.g.,disk dryers, conveyor dryers, fluidized bed dryers, or infrared dryers)are used for the heat treatment of the product.

Step 3) Subsequently, the ionic cross-linking agent, preferably aluminumdihydroxyacetate stabilized with boric acid, is thoroughly mixed withthe obtained material at room temperature until a homogeneous mixtureresults. For fixation purposes of the cross-linking agent by the matrix,heating to 25° C. to 180° C., preferably to 50° C. to 80° C., for 5 to60 minutes is effected again in order to melt the matrix material.

Instead of the processing described in step 1, component A mayoptionally be incorporated into a swollen (e.g., with water) componentB, or the component B may be incorporated into the swollen (e.g., withwater) component A, or the swollen (e.g., with water) component A may beincorporated into the swollen (e.g., with water) component B, optionallyunder the addition of water or an aqueous solution.

After grinding (step 1 ), the product may be screened, preferably to aparticle size of 90-630 μm.

The incorporation of the matrix components is preferably effected atroom temperature, however, the matrix component may also be used as amelt. Prior to the thermal modification, an admixture preferablyconsisting of water/isopropanol may be added to the mixture in step 2,in order to have a solubilizer. Water and other admixtures of water withwater-soluble organic solvents may also be used instead of thewater/isopropanol-mixture. EP-PS 0 083 022 describes the cross-linkageof an absorber, which consists of polyacrylic acid, with cross-linkingagents comprising at least two functional groups and being able to reactwith the carboxyl groups of the polyacrylate. The reaction takes placeat the surface of the absorber particles. DE-PS 33 14 019 and DE-PS 3523 617 also describe the surface cross-linkage of polyacrylates by meansof cross-linking agents having at least two functional groups. Incontrast to the absorbers according to the present invention, thesepatents only describe modifications of polyacrylates--but not ofpolysaccharides--in the shell, however, this does by no means result inabsorbers having a sufficient bio-degradability.

The incorporation of the ionic cross-linking agent may also be effecteddirectly into the physical mixture of step 2, whereupon heating to 25°C. to 180° C., preferably to 100° C. to 120° C. is effected for 5 to 120minutes, preferably 20 to 60 minutes. In this process theabove-mentioned solvent-step may be effected either prior to or afterthe incorporation of the cross-linking agent.

The covalent cross-linking agent may be added to the polymer mixture asan alternative and in addition to the ionic cross-linking agent, eitherprior to or after the matrix addition. The covalent cross-linking agentis dissolved in a preferably optional alcohol/water-mixture and droppedinto the polymer mixture under rapid stirring. The quantity of solventamounts to between 1 and 10%, relative to the polymeric mixture.Subsequently, heating to 25° C. to 180° C. is effected for 5 to 120minutes. Water and mixtures of water with water-soluble organic solventsmay be used as solvents.

Optionally, the anti-blocking agents as well as the covalentcross-linking agent may also already the added in step 1).

The absorbent material according to the present invention has a goodbiodegradability, as compared to products based on polyacrylic acid,with a considerably improved absorption and suction capacity for a 0.9%solution of sodium chloride, also under load, as compared to knownabsorbents on a native basis, and a surprisingly very high gel strength.

    ______________________________________                                        Gel strength of some absorbers according to the present invention             and some commercially known absorbers                                                             Gel strength (10 Hz)                                      Product name        (N/m.sup.2)                                               ______________________________________                                        Absorbers according to the invention                                          superabsorber of Example 1                                                                        ≧10000                                             superabsorber of Example 3                                                                        ≧10000                                             superabsorber of Example 5                                                                        ≧10000                                             superabsorber of Example 7                                                                        ≧10000                                             superabsorber of Example 9                                                                        ≧10000                                             Commercially known Absorbers                                                  Product A           2450                                                      Product B           4200                                                      Product C           3500                                                      Product D           2700                                                      Product E           4950                                                      Product F           3700                                                      Product G           1575                                                      ______________________________________                                         Products A, B, C, D, F, and G:                                                crosslinked, partially neutralized polyacrylates                              Product E:                                                                    crosslinked, partially neutralized polyacrylatestarch-graft polymer.     

Additionally, the mechanical strength (with respect to disintegrationinto the individual components) is considerably improved as compared tothe previously described absorbers based on renewable raw materials.

The polymer composition according to the present invention mayparticularly be used as absorbent as a fiber, film, powder, or granularmaterial to absorb water or aqueous liquids, such as urine and blood,and therefore is particularly suitable for the use in diapers, tampons,surgical products, cable sheathings, culture pots, packaging materialsfor meat or fish, and in absorbent garments.

Additionally, the material is suitable as storage medium for the gradualrelease of active substances, such as drugs, pesticides (U.S. Pat. Nos.4,818,534; 4,983,389; 4,983,390; 4,985,251) and fragrances, having theadvantage that the storage medium is degradable. Therefore, anadditional advantage results in the fact that the active substance isreleased completely. The active substance-containing depot materials maybe manufactured by absorption, preferably of concentrated, aqueous orhydrous solutions into the substantially dry absorber, and reneweddrying, if necessary.

The active substance may also be added directly or as a solution ordispersion in any previous stage of the production process of theabsorber composition.

The active substance-containing depot materials are used in the form ofa powder or as a dispersion in hydrophobic media, which may comprisedispersion-stabilizing agents, such as emulsifiers or stabilizers, or inadmixture with other substances, such as polysaccharides.

For instance, the addition of these bactericide-containing depotmaterials to cellulose, guar or starch products or their derivatives,such as carboxymethylcellulose, prevents the decomposition of thesesubstances during storage and application in aqueous media over a longerperiod of time, thus avoiding larger amounts of free active substance inthe solution owing to the depot effect.

Test Methods

Tea Bag Test (TBT)

To determine the absorption capacity a tea bag test was carried out. Anaqueous 0.9% NaCl-solution was used as test solution. 0.2 g of a testsubstance (screened to between 90 and 630 μm), which had been weighedinto a tea bag, was allowed to swell in the test solution for 10 and 30minutes, respectively. After dripping for 5 minutes (maximum value),centrifuging was effected in a centrifuge, e.g., in a commercial spindryer, at 1400 rpm. The liquid absorption was determined gravimetricallyand expressed in terms of 1 g of substance (retention value).

Absorption under Load (AUL)

To determine the liquid absorption capacity under a load, the absorptionunder load--as described in EP-A 0 339 461 --was determined. 0.16 g testsubstance (screened to between 300 and 600 μm) was allowed to swell bycapillary action in 0.9% NaCl-solution for 60 minutes under a pressureof 1.55 kN/m² (99.8 g/in²). The liquid absorption was determinedgravimetrically and expressed in terms of 1 g of substance.

Gel strength (G')

To determine the gel strength G' of the swollen absorbers the methoddescribed in EP-A 0 339 461 was used. Apparatus: Controlled StressRheometer CS 100, Carri-Med Ltd. Dorking/UK. Measurement conditions:Plate-plate-system, diameter 60 mm, space between plates 2 mm,temperature 20° C., torque 1000-4000 μNm, amplitude 1.5-5 mrad,frequency 10.0 Hz, 28 ml 0.9% NaCl/g absorber. The indications are givenin N/m².

Flow Test (FT)

By means of the flow test the velocity at which the products absorbedthe test liquid was determined; moreover, it was examined whether theyshowed blocking phenomena, were completely swollen and whether they werewetted all over. Furthermore, it was examined whether the gels werepresent in a solid, tacky or loose and separated form.

To carry out the flow test, about 100 mg of substance were placed on awater-soaked paper cloth, and the water absorption by the products wasobserved. The absorption behavior was evaluated according to thefollowing graduation:

A: is absorbed rapidly

B: is absorbed very rapidly

C: is absorbed from beginning to end

D: after water absorption, gel is present in separated form

E: gel blocking.

The present invention will be illustrated in more detail in thefollowing by means of production and application examples.

Pre-products

Each of the following mixtures are stirred into 360 ml of water at roomtemperature (15° to 20° C.) and allowed to stand for three hours.Subsequently, the resulting gels are dried at 100° C. in therecirculating air dryer for two hours and then ground and screened to aparticle size of 90-630 μm.

Pre-product 1

38 g C.M.C. Walocel 40000 (sodium carboxymethylcellulose, product ofWolff Walsrode), 2 g of a polyacrylate superabsorber (manufacturedaccording to DE-OS 40 15 085, example 4, referred to "SAB A" in thefollowing).

Pre-product 2

38 g C.M.C. (Walocel 30000), 2 g "SAB A"

Pre-product 3

36 g C.M.C. (Walocel 30000), 4 g "SAB A"

Pre-product 4

32 g C.M.C. (Walocel 30000), 8 g "SAB A"

Pre-product 5

32 g C.M.C (Walocel 30000), 8 g "SAB A", 4 g cellulose fiber (PWC 500,product of Rettenmaier).

Pre-product 6

28.5 g C.M.C. (Walocel 30000), 9.5 g guar flour (type 104, product ofRoeper), 2 g "SAB A"

Pre-product 7 (comparative product)

40 g C.M.C. (Walocel 40000) without additive

EXAMPLES Example 1

5 g of pre-product 1 is thoroughly mixed with 0.25 g (cellulose,diameter: 17 μm, length: 30 μm) fiber BE 600/30 (product ofRettenmaier), and 0.25 g acid-terminated TONE 230 is (a reaction productof TONE 230, polyol based on caprolactone, molecular weight 1250 g.mol⁻¹, product of Union Carbide, and maleic anhydride) and then heatedin the oven to 120° C. for 30 minutes. Then 0.25 g Al(OH)₂ OOCCH₃ *1/3H₃BO₃ is added followed by heating to 50° C. in the oven for one hour.

TBT (max./ret.)=48 g/g / 26 g/g; AUL=18.0 g/g; FT: B C D

Example 2

5 g of pre-product 2 is thoroughly mixed with 0.25 g Aerosil R 972(fumed silica, particle diameter: 16 nm, product of Degussa AG), 0.25 gacid-terminated TONE 230, 0.5 ml water, and 1 ml i-propanol and thenheated in the oven to 120° C. for 30 minutes. Then, 0.25 g Al(OH)₂OOCCH₃ *1/3H₃ BO₃ is added followed by heating to 50° C. in the oven forone hour.

TBT (max./ret.)=51 g/g / 28 g/g; AUL=19.6 g/g; FT: B C D

Example 3

Procedure as in Example 2, however, pre-product 3 is used instead ofpre-product 2, furthermore, Aerosil A 200 (fumed silica, particlediameter: 12 nm, Degussa AG) is used instead of Aerosil R 972.

TBT (max./ret.)=45 g/g / 27 g/g; AUL=17.0 g/g; FT: B C D

Example 4

Procedure as in Example 2, however, pure TONE 230 is used instead ofacid-terminated TONE 230; furthermore, thorough mixing is effected withtwice the amount of water and twice the amount of i-propanol.

TBT (max./ret.)=52 g/g / 29 g/g; AUL=19.0 g/g; FT: B C D

Example 5

Procedure as in Example 2, however, pre-product 5 is used.

TBT (max./ret.)=47 g/g / 27 g/g; AUL=18.3 g/g; FT: B C D

Example 6

Procedure as in Example 3, however, only half the amount 5 ofacid-terminated TONE 230 is used, and Aerosil A 200 is replaced by thesame amount of fiber BE 600/30.

TBT (max./ret.)=52 g/g / 29 g/g; AUL=18.7 g/g; FT: B C D

Example 7

Procedure as in Example 2, however, (prior to the first heating) 0.25 gfiber BE 600/30 is additionally incorporated.

TBT (max./ret.)=49 g/g / 28 g/g; AUL=18.9 g/g; FT: B C D

Example 8

Procedure as in Example 2, however, pre-product 6 is used.

TBT (max./ret.)=38 g/g / 22 g/g; AUL=16.5 g/g; FT: A C D

Example 9

Procedure as in Example 2, however, pre-product 5 is used, and theamount of aluminum cross-linker is reduced to 0.2 g.

TBT (max./ret.)=49 g/g / 28 g/g; AUL=16.8 g/g; FT: A C D

Example 10

100 g of the product obtained in Example 1 is mixed with 100 ml of a0.125% aqueous solution of 3,7-bis (dimethylamino)-phenothiaziniumchloride and then dried at 60° C. in the recirculating air dryer for 2h. 200 mg of the product thus obtained are placed in a tea bag. This issuspended in a beaker with 50 ml 0.2% solution of sodium chloride. Afterone hour, the tea bag is removed. The dye of the sodium chloridesolution is assessed, then the procedure is repeated with freshNaCl-solution. Even after the 5th cycle, the blueness of the sodiumchloride solution shows the release of the active substance from thepolymer composition serving as storage medium.

Example 11

In the preparation of pre-product 1, 0.05 g of 3,7-bis(dimethylamino)--phenothiazinium chloride is additionally added to thepowder mixture, and the further processing is as described. According toExample 1, an absorber is prepared from this pre-product. The absorberthus prepared is examined as in Example 10. The obtained results are thesame as in Example 10.

COMPARATAIVE EXAMPLES Comparative Example 1

Procedure as in Example 2, however, pre-product 7 and half the amount ofacid-terminated TONE 230 is used.

TBT (max./ret.)=36 g/g / 27 g/g; AUL=8.0 g/g; FT: E

Comparative Example 2

20 g C.M.C. 30000 is kept at 50° C. for 4 hours with 8 g isopropanol,200 g water, 0.4 g Al(OH)₂ OOCCH₃ *1/3H₃ BO₃, and 0.8 g acetic acid.Then drying at 80° C. follows.

TBT (max./ret.)=16 g/g / 11 g/g; AUL=8.9 g/g; FT: E

Comparative Examples 3, 4

The manufacture of the products according to Examples 3 and 5 wasrepeated without the addition of a matrix material. The products soobtained were inhomogeneous, could be separated by screening andblocked. With respect to the TBT and AUL-test, no reproducible valuescould be obtained because of the inhomogeneity of the products(separation during screening).

Comparative Example 5

60 g C.M.C. 40000 is thoroughly mixed with 1.5 g ethylene carbonate, 1.5ml water, and 1.5 ml isopropanol followed by heating to 120° C. for 60min. in the oven. 8 g of this product is thoroughly mixed with 2 gFavor® 953 (cross-linked, partially neutralized polyacrylate, product ofStockhausen GmbH), 0.5 g TONE 230, 0.5 g fiber BE 600/30, and 0.5 gAl(OH)₂ OOCCH₃ *1/3H₃ BO₃ by using 2 ml isopropanol and 1 ml water, andheated to 120° C. for 60 min. in the oven.

TBT (max./ret.)=46 g/g / 29 g/g; AUL=14.4 g/g; FT: B C D

Comparative Example 6

8 g C.M.C. 40000 is thoroughly mixed with 2 g "SAB A", 0.5 g fiber BE600/30, 0.5 g acid-terminated TONE 230, 0.1 g Aerosil R 972, 2 mli-propanol and 1 ml water, and then heated for 30 minutes to 120° C. inthe oven. 0.6 g Al(OH)₂ OOCCH₃ *1/3H₃ BO₃ is added to the product thusobtained, followed by heating in the oven to 50° C. for one hour.

TBT (max./ret.)=51 g/g / 36 g/g; AUL=11.0 g/g; FT: B C D

We claim:
 1. An absorbent polymer composition comprising:(A)70-99.99%-wt. of component A, wherein said component A is awater-soluble or water-swellable polysaccharide or a polysaccharidederivative selected from the group consisting of carboxymethyl guar,hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcelluloseand carboxymethyl starch, which polysaccharide or polysaccharidederivative may optionally be modified by cross-linkage, and (B)0.01-30%-wt. of component B, wherein said component B is awater-swellable, synthetic polymer or copolymer of polymeric subunitsselected from the group consisting of (meth-)acrylic acid,(meth-)acrylonitrile, (meth-)acrylamide, vinyl acetate, vinylpyrrolidone, vinyl pyridine, maleic acid or anhydride, itaconic acid oranhydride, fumaric acid, vinyl sulfonic acid,2-acrylamido-2-methylpropane sulfonic acid, and the amides, the N-alkylderivatives, the N,N'-dialkyl derivatives, the hydroxyl group-containingesters, and the amino group-containing esters of said subunits,wherein0-98%-wt. of any acid groups may be neutralized, and wherein saidpolymer or copolymer is cross-linked by an at least bifunctionalcompound, wherein the recited weight percentages of said components Aand B are based on the total weight of components A and B, and (C)0.1-30%-wt., relative to said polymer components A and B, of an organicmatrix material having a melting or softening point, respectively, ofbelow 180° C., wherein said matrix material prevents separation and gelblocking of said absorbent polymer composition, and (D) 0.001 to10%-wt., relative to said two polymer components A and B, of an ionic orcovalent cross-linking agent, wherein said cross-linking agentcross-links said components A and B with each other, and (E) 0-50%-wt.,relative to said polymer components A and B, of at least oneanti-blocking agent,wherein said absorbent polymer composition is madeby a process comprising the steps of:bringing said component B togetherwith said component A in an aqueous medium, subsequently drying andgrinding the resulting mixture, adding said matrix material (C) and saidanti-blocking agent (E), mixing the resulting mixture to homogeneity,carrying out a first heat treatment, adding said cross-linking agent(D), and optionally carrying out a second heat treatment.
 2. An activesubstance-containing composition comprising the absorbent polymercomposition according to claim 1 and at least one active substance,wherein said active substance is releasable from said activesubstance-containing composition in a retarded manner.
 3. Thecomposition according to claim 1, wherein said composition comprises75-95%-wt. of said component A, 5-25%-wt. of said component B,2.5-7.5%-wt., relative to said components A and B, of at least one saidorganic matrix material (C), 3-7%-wt., relative to said components A andB, of at least one said ionic or covalent cross-linking agent (D), and0.5-50%-wt., relative to said components A and B, of at least one saidanti-blocking agent (E).
 4. The composition according to claim 1 whereinsaid polysaccharide or polysaccharide derivative is selected from thegroup consisting of guar, starch, cellulose, carboxymethyl guar,hydroxyethylcellulose, hydroxroypropylcellulose, carboxymethylcelluloseand carboxymethyl starch.
 5. The composition according to claim 1wherein the matrix material is selected from the group consisting oftriglycerol monostearate, castor oil and polycaprolactones, which areoptionally modified by a reaction with maleic anhydride.
 6. Thecomposition according to claim 1, wherein the ionic cross-linking agent(D) is selected from the group consisting of metallic compounds in theform of their salts with organic and inorganic acids.
 7. The compositionaccording to claim 1, wherein the covalent cross-linking agent (D) is acompound selected from the group consisting of polyfunctional carboxylicacids, alcohols, amines, epoxy compounds, carboxylic acid anhydrides,and aldehydes, and heterofunctional compounds comprising at least twofunctional groups of compounds selected from the group consisting ofpolyfunctional carboxylic acids, alcohols, amines, epoxy compounds,carboxylic acid anhydrides, and aldehydes.
 8. A process for theproduction of an absorbent polymer composition comprising:(A)70-99.99%-wt. of component A, wherein said component A is awater-soluble or water-swellable polysaccharide, or a polysaccharidederivative selected from the group consisting of carboxymethyl guar,hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcelluloseand carboxymethyl starch, which polysaccharide or polysaccharidederivative may optionally be modified by cross-linkage, and (B)0.01-30%-wt. of component B, wherein said component B is awater-swellable, synthetic polymer or copolymer of polymeric subunitsselected from the group consisting of (meth-)acrylic acid, (meth-)acrylonitrile, (meth-) acrylamide, vinyl acetate, vinyl pyrrolidone,vinyl pyridine, maleic acid or anhydride, itaconic acid or anhydride,fumaric acid, vinyl sulfonic acid, and 2-acrylamido-2-methylpropanesulfonic acid, and the amides, the N-alkyl derivatives, the N,N'-dialkylderivatives, the hydroxyl group-containing esters, and the aminogroup-containing esters of said subunits,wherein 0-98%-wt. of any acidgroups may be neutralized, and wherein said polymer or copolymer iscross-linked by an at least bifunctional compound, wherein the recitedweight percentages of said components A and B are based on the totalweight of components A and B, and (C) 0.1-30%-wt., relative to saidpolymer components A and B, of an organic matrix material having amelting or softening point, respectively, of below 180° C., wherein saidmatrix material prevents separation and gel blocking of said absorbentpolymer composition, and (D) 0.001 to 10%-wt., relative to said twopolymer components A and B, of an ionic or covalent cross-linking agent,wherein said cross-linking agent cross-links said components A and Bwith each other, and (E) 0-50%-wt., relative to said polymer componentsA and B, of at least one anti-blocking agent,which process comprises thesteps of: bringing said component B together with said component A in anaqueous medium, subsequently drying and grinding the resulting mixture,adding said matrix material (C) and said anti-blocking agent (E), mixingthe resulting mixture to homogeneity, carrying out a first heattreatment, adding said cross-linking agent (D), and optionally carryingout a second heat treatment.
 9. The process according to claim 8,wherein said composition comprises 75-95%-wt. of said component A,5-25%-wt. of said component B, 2.5-7.5%-wt., relative to said componentsA and B, of at least one said organic matrix material (C), 3-7%-wt.;relative to said components A and B, of at least one said ionic orcovalent cross-linking agent (D), and 0.5-50%-wt., relative to saidcomponents A and B, of at least one said anti-blocking agent (E). 10.The process according to claim 8, wherein said polysaccharide orpolysaccharide derivative is selected from the group consisting of guar,starch, cellulose, carboxymethyl guar, hydroxyethylcellulose,hydroxypropylcellulose, carboxymethylcellulose and carboxymethyl starch.11. The process according to claim 10 wherein the matrix material isselected from the group consisting of triglycerol monostearate, castoroil and polycaprolactones, which are optionally modified by a reactionwith maleic anhydride.
 12. The process according to claim 10 wherein theionic cross-linking agent (D) is selected from the group consisting ofmetallic compounds, in the form of their salts with organic andinorganic acids.
 13. The process according to claim 8, wherein thecovalent cross-linking agent (D) is a compound selected from the groupconsisting of polyfunctional carboxylic acids, alcohols, amines, epoxycompounds, carboxylic acid anhydrides, and aldehydes, andheterofunctional compounds comprising at least two functional groups ofcompounds selected from the group consisting of polyfunctionalcarboxylic acids, alcohols, amines, epoxy compounds, carboxylic acidanhydrides, and aldehydes.
 14. The process of claim 8, wherein saidcomponent B is mixed with said component A in an aqueous medium, saidcomponents A and B are then swollen in a hydrous solution or dispersion,and the resulting mixture is dried and ground.
 15. The process accordingto claim 14, wherein both of said polymer components A and B are mixedin dry form or one of said components A and B in dry form is mixed withthe other of said components A and B which is already swollen by meansof a hydrous solution or dispersion.
 16. The process according to claim8, wherein said component B is swollen by a hydrous solution ordispersion and is mixed with said component A which is swollen by ahydrous solution or dispersion, optionally under the addition of ahydrous solution or dispersion, and wherein the resulting mixture isdried and ground.
 17. The process according to claim 1, wherein themixing of the polymer components and the mixing of the other componentsis effected at temperatures of 0° C. to 100° C.
 18. The processaccording to claim 17, wherein the drying is effected at 40° C. to 180°C. and the ground product is screened to a particle size of 90 to 630μm.
 19. The process according to claim 1, wherein said first heattreatment is carried out at 25° C. to 180° C., and said optional secondheat treatment is carried out at 25° C. to 180° C.
 20. The processaccording to claim 1, wherein following the grinding, said organicmatrix material and said anti-blocking agent are admixed in the presenceof a hydrous solution or dispersion.
 21. The process according to claim1, wherein the cross-linking agent is dissolved or dispersed in amixture of water and/or a hydrous organic solvent and added to thepolymer components to be contacted or to the other components, prior tosaid first heat treatment.
 22. The absorbent composition according toclaim 1, wherein said composition is contained in a fiber, film, powder,or granular material.
 23. A composition comprising the absorbentcomposition of claim 2, wherein said absorbent composition is in theform of a powder or is dispersed in hydrophobic media.
 24. An activesubstance-containing composition according to claim 2, wherein saidactive substance is selected from the group consisting of a drug, apesticide, a bactericide, and a perfume.
 25. A composition according toclaim 4, wherein component A is carboxymethylcellulose.
 26. Acomposition of claim 6, wherein said metal compounds are selected fromthe group consisting of magnesium, calcium, aluminum, zirconium, iron,titanium, and zinc compounds.
 27. A process according to claim 9,wherein said composition comprises 5-15%-wt., relative to saidcomponents A and B, of said at least one anti-blocking agent.
 28. Aprocess according to claim 10, wherein component A iscarboxymethylcellulose.
 29. A process according to claim 12, whereinsaid metal compounds are selected from the group consisting ofmagnesium, calcium, aluminum, zirconium, iron, titanium, and zinccompounds.
 30. A process according to claim 17, wherein said mixingoccurs at room temperature.
 31. A process according to claim 19, whereinsaid first heat treatment is carried out at from 100° C. to 120° C., andsaid optional second heat treatment is carried out at from 50° C. to 80°C.
 32. A process according to claim 20, wherein said matrix material andsaid anti-blocking agent are admixed in the presence of water or amixture of water and a hydrous organic solvent.
 33. An articlecomprising the absorbent composition of claim 22, wherein said articleis selected from the group consisting of packaging materials, culturepots, cable sheathing, tampons, diapers and animal hygiene products. 34.A composition of claim 23, wherein said composition further comprises adispersion stabilizer.
 35. A process according to claim 8, furthercomprising the steps of contacting said absorbent polymer compositionwith an aqueous or hydrous solution comprising an active agent, andoptionally drying the resulting mixture, thereby forming a depotmaterial composition.
 36. A process according to claim 8, furthercomprising the step of adding an active agent to the mixture at any ofthe steps, thereby forming a depot material composition.
 37. Thecomposition according to claim 1, wherein the covalent cross-linkingagent (D) is a compound selected from the group consisting of citricacid, mucic acid, tartaric acid, malic acid, malonic acid, succinicacid, glutaric acid, adipic acid, polyethylene glycols, glycerol,propanediols, polyoxypropylene amines, epichlorohydrin, ethylene glycoldiglycidyl ether, glycol diglycidyl ether, succinic anhydride, maleicanhydride, ethylene carbonate and propylene carbonate, andheterofunctional compounds comprising at least two functional groups ofcompounds selected from the group consisting of citric acid, mucic acid,tartaric acid, malic acid, malonic acid, succinic acid, glutaric acid,adipic acid, polyethylene glycols, glycerol, propanediols,polyoxypropylene amines, epichlorohydrin, ethylene glycol diglycidylether, glycol diglycidyl ether, succinic anhydride, maleic anhydride,ethylene carbonate and propylene carbonate.
 38. The process according toclaim 8, wherein the covalent cross-linking agent (D) is a compoundselected from the group consisting of citric acid, mucic acid, tartaricacid, malic acid, malonic acid, succinic acid, glutaric acid, adipicacid, polyethylene glycols, glycerol, propanediols, polyoxypropyleneamines, epichlorohydrin, ethylene glycol diglycidyl ether, glycoldiglycidyl ether, succinic anhydride, maleic anhydride, ethylenecarbonate and propylene carbonate, and heterofunctional compoundscomprising at least two functional groups of compounds selected from thegroup consisting of citric acid, mucic acid, tartaric acid, malic acid,malonic acid, succinic acid, glutaric acid, adipic acid, polyethyleneglycols, glycerol, propanediols, polyoxypropylene amines,epichlorohydrin, ethylene glycol diglycidyl ether, glycol diglycidylether, succinic anhydride, maleic anhydride, ethylene carbonate andpropylene carbonate.